Effect of lameness on milk production loss in Thai dairy cows

Introduction 
Being aware of the impact of lameness on milk production is necessary to encourage dairy cow farmers to pay more attention to this problem. Most farmers in Thailand consider lameness as a minor problem because they have limited information about the production loss caused by lameness. Although the prevalence of lameness in Thailand is high, it is always underestimated by farmer. Therefore, we need the evidences that clearly present the production loss due to lameness. The results of our study would allow farmer to realize the importance of lameness on the milk production loss. This study aimed to examine the impact of lameness on daily milk production based on information obtained from cow level in two large dairy farms in Thailand 

Materials and Methods 
The locomotion score (LS) of each 75-87.5% Holstein Friesian cow in two large dairy farms was evaluated monthly for consecutive 8 months. LS was scored following Sprecher et al. (1997). LS were separated into 3 groups: LS 1 was identified as non-lameness group, LS2-3 was in subclinical lameness group, and LS 4-5 was in clinical lameness group. The cows’ data was obtained from farm database recording in Dairy Champ software consisted of lactation number, breed, lameness, mastitis, metritis, and other medical records. Individual lactation curve was simulated using test daily milk yield data with non-linear regression model as explained in Inchaisri et al. (2009). To analyses the factors related with daily milk production (kg/day), the multivariable generalized linear mixed model was performed accounting for the correlation of repeated measures of milk yield within an individual lactation by taking lactation number of each cow ID as random effect. In the analysis, the dependent variable was an estimated daily milk production. Independent variables included farm ID, lactation number, DIM, locomotion score, clinical mastitis, and metritis. Variables associated with daily milk yield will be examined for statistical significance and interaction at p<0.05. […]